1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
# frozen_string_literal: true
module Gitlab
class SSHPublicKey
Technology = Struct.new(:name, :key_class, :supported_sizes, :supported_algorithms)
# See https://man.openbsd.org/sshd#AUTHORIZED_KEYS_FILE_FORMAT for the list of
# supported algorithms.
TECHNOLOGIES = [
Technology.new(:rsa, SSHData::PublicKey::RSA, [1024, 2048, 3072, 4096], %w(ssh-rsa)),
Technology.new(:dsa, SSHData::PublicKey::DSA, [1024, 2048, 3072], %w(ssh-dss)),
Technology.new(:ecdsa, SSHData::PublicKey::ECDSA, [256, 384, 521], %w(ecdsa-sha2-nistp256 ecdsa-sha2-nistp384 ecdsa-sha2-nistp521)),
Technology.new(:ed25519, SSHData::PublicKey::ED25519, [256], %w(ssh-ed25519)),
Technology.new(:ecdsa_sk, SSHData::PublicKey::SKECDSA, [256], %w(sk-ecdsa-sha2-nistp256@openssh.com)),
Technology.new(:ed25519_sk, SSHData::PublicKey::SKED25519, [256], %w(sk-ssh-ed25519@openssh.com))
].freeze
BANNED_SSH_KEY_FINGERPRINTS = [
# https://github.com/rapid7/ssh-badkeys/tree/master/authorized
# banned ssh rsa keys
"SHA256:Z+q4XhSwWY7q0BIDVPR1v/S306FjGBsid7tLq/8kIxM",
"SHA256:uy5wXyEgbRCGsk23+J6f85om7G55Cu3UIPwC7oMZhNQ",
"SHA256:9prMbqhS4QteoFQ1ZRJDqSBLWoHXPyKB0iWR05Ghro4",
"SHA256:1M4RzhMyWuFS/86uPY/ce2prh/dVTHW7iD2RhpquOZA",
# banned ssh dsa keys
"SHA256:/JLp6z6uGE3BPcs70RQob6QOdEWQ6nDC0xY7ejPOCc0",
"SHA256:whDP3xjKBEettbDuecxtGsfWBST+78gb6McdB9P7jCU",
"SHA256:MEc4HfsOlMqJ3/9QMTmrKn5Xj/yfnMITMW8EwfUfTww",
"SHA256:aPoYT2nPIfhqv6BIlbCCpbDjirBxaDFOtPfZ2K20uWw",
"SHA256:VtjqZ5fiaeoZ3mXOYi49Lk9aO31iT4pahKFP9JPiQPc",
# other banned ssh keys
# https://github.com/BenBE/kompromat/commit/c8d9a05ea155a1ed609c617d4516f0ac978e8559
"SHA256:Z+q4XhSwWY7q0BIDVPR1v/S306FjGBsid7tLq/8kIxM",
# https://www.ctrlu.net/vuln/0006.html
"SHA256:2ewGtK7Dc8XpnfNKShczdc8HSgoEGpoX+MiJkfH2p5I"
].to_set.freeze
def self.technologies
if Gitlab::FIPS.enabled?
Gitlab::FIPS::SSH_KEY_TECHNOLOGIES
else
TECHNOLOGIES
end
end
def self.technology(name)
technologies.find { |tech| tech.name.to_s == name.to_s }
end
def self.technology_for_key(key)
technologies.find { |tech| key.instance_of?(tech.key_class) }
end
def self.supported_types
technologies.map(&:name)
end
def self.supported_sizes(name)
technology(name).supported_sizes
end
def self.supported_algorithms
technologies.flat_map { |tech| tech.supported_algorithms }
end
def self.supported_algorithms_for_name(name)
technology(name).supported_algorithms
end
def self.sanitize(key_content)
ssh_type, *parts = key_content.strip.split
return key_content if parts.empty?
parts.each_with_object(+"#{ssh_type} ").with_index do |(part, content), index|
content << part
if self.new(content).valid?
break [content, parts[index + 1]].compact.join(' ') # Add the comment part if present
elsif parts.size == index + 1 # return original content if we've reached the last element
break key_content
end
end
end
attr_reader :key_text, :key
def initialize(key_text)
@key_text = key_text
# We need to strip options to parse key with options or in known_hosts
# format. See https://man.openbsd.org/sshd#AUTHORIZED_KEYS_FILE_FORMAT
# and https://man.openbsd.org/sshd#SSH_KNOWN_HOSTS_FILE_FORMAT
key_text_without_options = @key_text.to_s.match(/(\A|\s)(#{self.class.supported_algorithms.join('|')}).*/).to_s
@key =
begin
SSHData::PublicKey.parse_openssh(key_text_without_options)
rescue SSHData::DecodeError
end
end
def valid?
key.present?
end
def type
technology.name if valid?
end
def fingerprint
key.fingerprint(md5: true) if valid?
end
def fingerprint_sha256
'SHA256:' + key.fingerprint(md5: false) if valid?
end
def bits
return unless valid?
case type
when :rsa
key.n.num_bits
when :dsa
key.p.num_bits
when :ecdsa
key.openssl.group.order.num_bits
when :ed25519
256
when :ecdsa_sk
256
when :ed25519_sk
256
end
end
def banned?
BANNED_SSH_KEY_FINGERPRINTS.include?(fingerprint_sha256)
end
private
def technology
@technology ||=
self.class.technology_for_key(key) || raise_unsupported_key_type_error
end
def raise_unsupported_key_type_error
raise("Unsupported key type: #{key.class}")
end
end
end
|
